Overvoltage suppression method of resonant direct-current transformer and resonant direct-current transformer

Abstract

The invention discloses an overvoltage suppression method of a resonant direct-current transformer and the resonant direct-current transformer, and relates to the technical field of power electronics. The overvoltage suppression method of the resonant direct-current transformer comprises the following steps: detecting a direct-current output voltage provided by a direct-current output port, and comparing the direct-current output voltage with an output voltage target value of the resonant direct-current transformer; and under the condition that the direct current output voltage is greater than the output voltage target value, dynamically adjusting the internal phase shift delay between the control signals of the first half bridge and the second half bridge so as to adjust the direct current output voltage to be less than or equal to the output voltage target value. According to the embodiment of the invention, the suppression cost of the light-load overvoltage of the resonant direct-current transformer can be reduced, and the reliability of the resonant direct-current transformer is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to a resonance type direct-current transformer overvoltage suppression method and a resonance type direct-current transformer. BACKGROUND

[0002] In recent years, with the rapid development of power electronics technology, direct-current transformers gradually become an important part of direct-current power distribution systems due to their high efficiency and flexibility. Direct-current transformers play a key role in realizing conversion between different voltage levels, improving power transmission efficiency, and optimizing system control. In particular, in the fields of renewable energy generation, electric vehicle charging, and data center power supply, direct-current transformers are increasingly widely used.

[0003] Among many direct-current transformer topologies, resonance type direct-current transformers have received widespread attention due to their high efficiency and soft switching characteristics. Resonance type direct-current transformers achieve efficient energy conversion through resonant circuits, which can maintain high conversion efficiency under a wide range of input voltage and load conditions. However, this type of transformer has some problems when operating at light load, which limits its performance and reliability in practical applications.

[0004] Specifically, the voltage gain of the resonance type direct-current transformer is too high at light load, which does not meet the theoretical value of the fundamental approximation method. The root cause of this problem lies in the parasitic capacitance of the input and output H-bridges. Under light load conditions, the parasitic capacitance becomes the dominant parameter in the resonance process, leading to changes in the resonance frequency and voltage gain. When the load is extremely light, the influence of the parasitic capacitance is particularly significant, and the light load overvoltage phenomenon occurs, which not only affects the normal operation of the direct-current transformer, but also may cause equipment damage, reducing the reliability and safety of the system. Therefore, how to solve the overvoltage problem of the resonance type direct-current transformer at light load or no-load operating conditions by changing the control strategy at low cost, and improve the reliability of the resonance type direct-current transformer, has become a key problem in engineering practice. SUMMARY

[0005] The embodiments of the application provide a resonance type direct-current transformer overvoltage suppression method and a resonance type direct-current transformer, which can reduce the suppression cost of the resonance type direct-current transformer light load overvoltage and improve the reliability of the resonance type direct-current transformer.

[0006] In a first aspect, the embodiments of the application provide a resonance type direct-current transformer overvoltage suppression method, and the resonance type direct-current transformer comprises an inverter full-bridge circuit, a resonant circuit, an isolation transformer, and a rectifier bridge circuit. The input end of the inverter full-bridge circuit is connected with the DC input port, the output end of the inverter full-bridge circuit is electrically connected with the input end of the resonant circuit, the output end of the resonant circuit is electrically connected with the primary winding of the isolation transformer, the secondary winding of the isolation transformer is electrically connected with the input end of the rectifier bridge circuit, and the output end of the rectifier bridge circuit is electrically connected with the DC output port. The inverter full-bridge circuit includes a first half-bridge and a second half-bridge arranged between the DC input port, and the overvoltage suppression method of the resonant DC transformer includes: The DC output voltage provided by the DC output port is detected, and the DC output voltage is compared with an output voltage target value of the resonant DC transformer; In the case that the DC output voltage is greater than the output voltage target value, the internal phase shift delay between the control signals of the first half-bridge and the second half-bridge is dynamically adjusted to adjust the DC output voltage to be less than or equal to the output voltage target value.

[0007] In some possible embodiments, the value of the internal phase shift delay is within a preset range; The upper limit value of the preset range is calculated based on physical parameters of the resonant DC transformer; The physical parameters include at least one of the following: the transformation ratio of the isolation transformer, the number of series-connected diodes in a single half-bridge in the rectifier bridge circuit, the resonant inductance in the resonant circuit, the parasitic capacitance of the secondary diode of the isolation transformer, and the dynamic voltage-sharing capacitance of the secondary diode of the isolation transformer.

[0008] In some possible embodiments, the value of the internal phase shift delay is within a preset range, including: The value of the internal phase shift delay satisfies a target relationship, and the target relationship includes:

[0009] Wherein, D is the internal phase shift delay, n is the transformation ratio of the isolation transformer, m is the number of series-connected diodes in a single half-bridge in the rectifier bridge circuit, is the resonant inductance in the resonant circuit, is the parasitic capacitance of the secondary diode of the isolation transformer, is the dynamic voltage-sharing capacitance of the secondary diode of the isolation transformer.

[0010] In some possible embodiments, in the case that the DC output voltage is greater than the output voltage target value, the internal phase shift delay between the control signals of the first half-bridge and the second half-bridge is dynamically adjusted, including: In the case that the DC output voltage is greater than the output voltage target value, the internal phase shift delay is increased by the output voltage closed-loop controller through proportional-integral control.

[0011] In some possible implementation manners, the overvoltage suppression method of the resonant DC transformer further includes: In a case where the DC output voltage is less than the output voltage target value, the output voltage closed-loop controller reduces the internal phase shift delay by proportional integral control, so that the resonant DC transformer is in a normal load working condition, and the internal phase shift delay is reduced to zero.

[0012] In some possible implementation manners, in a case where the resonant DC transformer is a three-phase resonant DC transformer, the inverter full-bridge circuit further includes a third half-bridge, and the overvoltage suppression method of the resonant DC transformer further includes: In a case where it is detected that the three-phase resonant DC transformer is in a light load or no-load working condition, the third half-bridge in the inverter full-bridge circuit is controlled to be turned off.

[0013] In some possible implementation manners, the resonant circuit includes a resonant capacitor and a resonant inductor; A first pole of the resonant capacitor is electrically connected to a first end of the output end of the inverter full-bridge circuit, a second pole of the resonant capacitor is electrically connected to a first end of the resonant inductor, and a second end of the resonant inductor is electrically connected to a first end of the primary winding of the isolation transformer; A second end of the output end of the inverter full-bridge circuit is electrically connected to a second end of the primary winding of the isolation transformer.

[0014] In some possible implementation manners, the first half-bridge includes a first switch module and a second switch module, and the second half-bridge includes a third switch module and a fourth switch module; A first end of the first switch module and a first end of the third switch module are electrically connected to a positive electrode connection of the DC input port; A second end of the first switch module and a first end of the second switch module are electrically connected to a first node, and a second end of the third switch module and a first end of the fourth switch module are electrically connected to a second node; A second end of the second switch module and a second end of the fourth switch module are respectively electrically connected to a negative electrode connection of the DC input port; The first node is electrically connected to a first end of the output end of the inverter full-bridge circuit, and the second node is electrically connected to a negative electrode connection of the output end of the inverter full-bridge circuit.

[0015] In some possible implementation manners, the rectifier bridge circuit includes a fourth half-bridge and a fifth half-bridge, the fourth half-bridge includes a fifth switch module and a sixth switch module, and the fifth half-bridge includes a seventh switch module and an eighth switch module; A first end of the fifth switch module and a first end of the seventh switch module are electrically connected to a first end of the DC output port; The second end of the fifth switch module and the first end of the sixth switch module are electrically connected to the first end of the secondary winding of the isolation transformer, and the second end of the seventh switch module and the first end of the eighth switch module are electrically connected to the second end of the secondary winding of the isolation transformer. The second end of the sixth switch module and the second end of the eighth switch module are electrically connected to the second end of the direct current output port; wherein the fifth switch module, the sixth switch module, the seventh switch module and the eighth switch module comprise at least one diode.

[0016] Based on the same inventive concept, in a second aspect, the embodiments of the present application provide a resonant DC transformer, the resonant DC transformer comprising an inverter full-bridge circuit, a resonant circuit, an isolation transformer and a rectifier bridge circuit; The input end of the inverter full-bridge circuit is connected with the direct current input port, the output end of the inverter full-bridge circuit is electrically connected with the input end of the resonant circuit, the output end of the resonant circuit is electrically connected with the primary winding of the isolation transformer, the secondary winding of the isolation transformer is electrically connected with the input end of the rectifier bridge circuit, and the output end of the rectifier bridge circuit is electrically connected with the direct current output port; The inverter full-bridge circuit comprises a first half-bridge and a second half-bridge arranged between the direct current input ports; The resonant DC transformer adopts the overvoltage suppression method of the resonant DC transformer according to any one of the embodiments of the first aspect of the present application.

[0017] Based on the same inventive concept, in a third aspect, the embodiments of the present application provide an overvoltage suppression device of a resonant DC transformer, the resonant DC transformer comprising an inverter full-bridge circuit, a resonant circuit, an isolation transformer and a rectifier bridge circuit; The input end of the inverter full-bridge circuit is connected with the direct current input port, the output end of the inverter full-bridge circuit is electrically connected with the input end of the resonant circuit, the output end of the resonant circuit is electrically connected with the primary winding of the isolation transformer, the secondary winding of the isolation transformer is electrically connected with the input end of the rectifier bridge circuit, and the output end of the rectifier bridge circuit is electrically connected with the direct current output port; The inverter full-bridge circuit comprises a first half-bridge and a second half-bridge arranged between the direct current input ports, and the overvoltage suppression device of the resonant DC transformer comprises: The first detection module is configured to detect a direct current output voltage provided by the direct current output port and compare the direct current output voltage with an output voltage target value of the resonant DC transformer; The first adjustment module is configured to, in the case that the direct current output voltage is greater than the output voltage target value, dynamically adjust an internal phase shift delay between control signals of the first half-bridge and the second half-bridge, so as to adjust an actual output voltage to be less than or equal to the output voltage target value.

[0018] In a fourth aspect, the embodiments of the present application provide a resonant DC transformer overvoltage suppression device, the resonant DC transformer overvoltage suppression device comprising: a processor and a memory storing computer program instructions; the processor implements the resonant DC transformer overvoltage suppression method provided in any one of the embodiments of the present application when executing the computer program instructions.

[0019] In a fifth aspect, the embodiments of the present application provide a computer readable storage medium, and the computer readable storage medium stores computer program instructions, and the computer program instructions are executed by a processor to implement the resonant DC transformer overvoltage suppression method provided in any one of the embodiments of the present application.

[0020] In a sixth aspect, the embodiments of the present application provide a computer program product, and instructions in the computer program product are executed by a processor of an electronic device to cause the electronic device to perform the resonant DC transformer overvoltage suppression method provided in any one of the embodiments of the present application.

[0021] The resonant DC transformer overvoltage suppression method and the resonant DC transformer provided by the embodiments of the present application can detect a DC output voltage provided by a DC output port, and compare the DC output voltage with an output voltage target value of the resonant DC transformer. In a case where the DC output voltage is greater than the output voltage target value, an internal phase shift delay between control signals of a first half-bridge and a second half-bridge is dynamically adjusted to adjust the DC output voltage to be less than or equal to the output voltage target value. In this way, the resonant DC transformer overvoltage suppression method and the resonant DC transformer provided by the embodiments of the present application can, in a case where an output voltage of the resonant DC transformer is higher than a rated value in a light load or no-load working condition, suppress the light load overvoltage with low control complexity without adding components, can reduce the suppression cost of the light load overvoltage of the resonant DC transformer, and improve the reliability of the resonant DC transformer. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0023] Figure 1 is a flowchart of the resonant DC transformer overvoltage suppression method provided by an embodiment of the present application; Figure 2 is a topological structure diagram of the resonant DC transformer provided by an embodiment of the present application; Figure 3 is a principle diagram of a resonant DC transformer switch control strategy provided by an embodiment of the present application; Figure 4 is a control block diagram of a resonant DC transformer overvoltage suppression method provided by an embodiment of the present application; Figure 5 is a structure diagram of a resonant DC transformer overvoltage suppression device provided by an embodiment of the present application; Figure 6 is a structure diagram of a resonant DC transformer overvoltage suppression device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0024] The features and exemplary embodiments of various aspects of the present application will be described in detail below with reference to the drawings. To make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, but not to limit the present application. The present application can be implemented without some of the specific details by those skilled in the art. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0025] It should be noted that, in this document, relational terms such as first and second, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the listed element.

[0026] As described in the background section, at present, when the resonant DC transformer is connected to a very light load, the influence of the parasitic capacitance is particularly significant, and the light-load overvoltage phenomenon may occur, which not only affects the normal operation of the DC transformer, but also may cause damage to the device, and reduces the reliability and safety of the system. Therefore, it is necessary to change the control strategy to solve the overvoltage problem of the resonant DC transformer under light-load or no-load working conditions at low cost.

[0027] At the present stage, the existing solutions include changing the frequency and changing the equivalent parasitic capacitance value of the rectifier bridge and the full-controlled device. However, the overvoltage phenomenon of the resonant DC transformer under light load also occurs at the above low switching frequency, which is difficult to suppress and cannot effectively improve the reliability of the DC transformer. And the method of reducing the parasitic capacitance value by connecting a capacitor in parallel with the rectifier bridge diode string and the full-controlled device can only suppress the overvoltage phenomenon, but will lead to the introduction of a large number of capacitor components, increasing the overall cost of the equipment.

[0028] In view of the above, for the case that the output voltage of the resonant DC transformer is higher than the rated value under light load, in order to solve the problems in the prior art, the embodiment of the present application provides an overvoltage suppression method of a resonant DC transformer and a resonant DC transformer. It should be noted that the embodiments provided by the present application are not intended to limit the scope of the present application.

[0029] Firstly, the overvoltage suppression method of the resonant DC transformer provided by the embodiment of the present application is introduced.

[0030] Figure 1 The flowchart of the overvoltage suppression method of the resonant DC transformer provided by an embodiment of the present application is shown. As shown in Figure 1 The overvoltage suppression method of the resonant DC transformer includes the following steps: S110, detecting the DC output voltage provided by the DC output port, and comparing the DC output voltage with the output voltage target value of the resonant DC transformer; S120, in the case that the DC output voltage is greater than the output voltage target value, dynamically adjusting the internal phase shift delay between the control signals of the first half-bridge and the second half-bridge to adjust the DC output voltage to be less than or equal to the output voltage target value.

[0031] The overvoltage suppression method of the resonant DC transformer provided by the embodiment of the present application detects the DC output voltage provided by the DC output port, and compares the DC output voltage with the output voltage target value of the resonant DC transformer. In the case that the DC output voltage is greater than the output voltage target value, the internal phase shift delay between the control signals of the first half-bridge and the second half-bridge is dynamically adjusted to adjust the DC output voltage to be less than or equal to the output voltage target value. In this way, the overvoltage suppression method of the resonant DC transformer provided by the embodiment of the present application can suppress the light load overvoltage without adding components, with low control complexity, which can reduce the suppression cost of the resonant DC transformer under light load, and improve the reliability of the resonant DC transformer.

[0032] To facilitate understanding of the above-mentioned overvoltage suppression method of the resonant DC transformer, the resonant DC transformer in the embodiments of the present application will be introduced first. Please refer to Figure 2 , Figure 2 is a schematic diagram of the topology of the resonant DC transformer provided by an embodiment of the present application. The above-mentioned resonant DC transformer provided by the present application can realize DC transformation and unidirectional power transmission, and is suitable for photovoltaic DC collection and other scenarios.

[0033] As shown in Figure 2 , the resonant DC transformer comprises an inverter full-bridge circuit 10, a resonant circuit 20, an isolation transformer T and a rectifier bridge circuit 30.

[0034] The input end of the inverter full-bridge circuit 10 is connected with a DC input port, and the output end of the inverter full-bridge circuit 10 is electrically connected with the input end of the resonant circuit 20. In the embodiment, the DC input port can be a LVDC (Low Voltage Direct Current) low-voltage DC port, which includes two positive and negative connection terminals, can be connected with a rectifier, energy storage, MPPT (Maximum Power Point Tracking) and other equipment with a DC power supply port, is responsible for the transmission of DC power, and is used for inputting a DC voltage Vp.

[0035] The above-mentioned inverter full-bridge circuit 10 is a full-bridge H-bridge, which is used for converting the DC signal provided by the DC input port into an AC signal. The inverter full-bridge circuit 10 includes a first half-bridge and a second half-bridge arranged between the DC input port. Figure 2 In some examples, the first half-bridge and the second half-bridge in the inverter full-bridge circuit 10 include a fully controlled power switch and an anti-parallel diode. The fully controlled power switch includes a gate turn-off thyristor, a high-power transistor, a power field effect transistor or an insulated gate bipolar transistor, etc., which is not strictly limited in the embodiments of the present application.

[0036] The output end of the resonant circuit 20 is electrically connected with the primary winding of the isolation transformer T, and the secondary winding of the isolation transformer T is electrically connected with the input end of the rectifier bridge circuit 30. The above-mentioned isolation transformer T plays a role of electrical isolation and voltage transformation, can prevent direct electrical connection between the input and the output, and thus improves the safety of the system.

[0037] The output end of the rectifier bridge circuit 30 is electrically connected with the direct current output port. The rectifier bridge circuit 30 can be used to convert alternating voltage into direct current voltage, so as to output the direct current voltage Vs through the direct current output port, to provide stable direct current power supply for the load. The direct current output port can be a high voltage direct current (HVDC) port. The rectifier bridge circuit 30 is a full-bridge H-bridge, and the bridge arm includes a diode.

[0038] Optionally, according to some embodiments of the present application, please continue to refer to Figure 2 The resonant circuit 20 includes a resonant capacitor C r and a resonant inductor L r . The first pole of the resonant capacitor C r is electrically connected with the first end of the output end of the inverter full-bridge circuit 10, the second pole of the resonant capacitor C r is electrically connected with the first end of the resonant inductor L r , and the second end of the resonant inductor L r is electrically connected with the first end of the primary winding of the isolation transformer T. The second end of the output end of the inverter full-bridge circuit 10 is electrically connected with the second end of the primary winding of the isolation transformer T.

[0039] In the embodiment, the resonant circuit 20 includes a resonant inductor L r and a resonant capacitor C r , in the form of LC series. The resonant inductor L r may be externally provided, or replaced by the leakage inductance of the isolation transformer T itself, so as to reduce the system cost and volume.

[0040] Optionally, according to some embodiments of the present application, the first half-bridge includes a first switch module 101 and a second switch module 102, and the second half-bridge includes a third switch module 103 and a fourth switch module 104. The first end of the first switch module 101 and the first end of the third switch module 103 are electrically connected with the positive pole of the direct current input port. The second end of the first switch module 101 and the first end of the second switch module 102 are electrically connected to the first node N1, and the second end of the third switch module 103 and the first end of the fourth switch module 104 are electrically connected to the second node N2. The second end of the second switch module 102 and the second end of the fourth switch module 104 are respectively electrically connected with the negative pole of the direct current input port. The first node N1 is electrically connected with the first end of the output end of the inverter full-bridge circuit 10, and the second node N2 is electrically connected with the negative pole of the output end of the inverter full-bridge circuit 10.

[0041] In the embodiment, in combination with Figure 2As shown, the first switch module 101 includes a fully controlled power switch T1 and its corresponding anti-parallel diode; the second switch module 102 includes a fully controlled power switch T2 and its corresponding anti-parallel diode; the third switch module 103 includes a fully controlled power switch T3 and its corresponding anti-parallel diode; and the fourth switch module 104 includes a fully controlled power switch T4 and its corresponding anti-parallel diode.

[0042] The aforementioned fully controllable power switch includes devices such as gate turn-off thyristors, high-power transistors, power MOSFETs, or insulated-gate bipolar transistors, but this embodiment does not impose strict limitations on these.

[0043] It should be added that the first half-bridge includes a first switch module 101 and a second switch module 102, and the second half-bridge includes a third switch module 103 and a fourth switch module 104.

[0044] Optionally, according to some embodiments of this application, the above-mentioned rectifier bridge circuit 30 includes a fourth half-bridge and a fifth half-bridge, the fourth half-bridge includes a fifth switch module 301 and a sixth switch module 302, and the fifth half-bridge includes a seventh switch module 303 and an eighth switch module 304. The first terminal of the fifth switch module 301 and the first terminal of the seventh switch module 303 are electrically connected to the first terminal of the DC output port; The second end of the fifth switch module 301 and the first end of the sixth switch module 302 are electrically connected to the first end of the secondary winding of the isolation transformer T, respectively; the second end of the seventh switch module 303 and the first end of the eighth switch module 304 are electrically connected to the second end of the secondary winding of the isolation transformer T, respectively. The second terminal of the sixth switch module 302 and the second terminal of the eighth switch module 304 are electrically connected to the second terminal of the DC output port; wherein, the fifth switch module 301, the sixth switch module 302, the seventh switch module 303 and the eighth switch module 304 include at least one diode.

[0045] In this embodiment, the fifth switch module 301 includes a diode D. 11 and diode D 12 The sixth switch module 302 mentioned above includes diode D. 21 and diode D 22 The aforementioned seventh switch module 303 includes diode D. 31 and diode D 32 The eighth switch module 304 mentioned above includes diode D. 41 and diode D 42 .

[0046] Thus, in the aforementioned rectifier bridge circuit 30, diodes are connected in series in each switching module to improve the output voltage withstand capability. It should be noted that... Figure 2 The example given is a rectifier bridge circuit 30 with two diodes connected in series. However, in practical applications, the number of diodes in the switching module can be one or more diodes connected in series.

[0047] It should be added that, in the above-mentioned rectifier bridge circuit 30, a dynamic voltage equalization capacitor C can also be connected in parallel across the two ends of any diode. bc And / or static equalizing resistors to ensure voltage balance among the series-connected devices.

[0048] Optionally, according to some embodiments of this application, the resonant DC transformer further includes: an input capacitor C. dcp and output capacitor C dcs ; Input capacitor C dcp The output capacitor C is positioned between the positive and negative terminals of the DC input port. dcs It is positioned between the positive and negative terminals of the DC output port.

[0049] In this embodiment, the aforementioned input capacitor C is provided between the positive and negative terminals of the DC input port. dcp The input capacitor C can filter out high-frequency noise and ripple in the input voltage. dcp By filtering, storing energy, and reducing voltage spikes, the input voltage is stabilized, reducing the impact of transient changes in the input voltage on the circuit.

[0050] By connecting the above output capacitor C in parallel between the positive and negative terminals of the DC output port. dcs This can further smooth the output voltage, reduce ripple, and improve the overall circuit performance and reliability. The aforementioned output capacitor C... dcs By smoothing the output voltage, storing energy, and reducing voltage spikes, the output voltage is stabilized, and the impact of load changes on the output voltage is reduced.

[0051] The specific implementation methods of steps 110 to 120 above are described in detail below.

[0052] In S110, specifically, the DC output voltage provided by the DC output port is detected, and the DC output voltage is compared with the target value of the output voltage of the resonant DC transformer.

[0053] In this embodiment, in a control system such as a resonant DC transformer, to ensure the stability and accuracy of the DC output voltage, the system monitors the DC output voltage in real time and compares it with a preset target output voltage value. Accurate measurement of the DC output voltage can be performed using a voltage sensor or similar device; this is not a limitation.

[0054] The aforementioned target output voltage value is preset based on the design requirements and load demands of the resonant DC transformer. This target output voltage value can be adjusted according to different operating modes of the resonant DC transformer and load conditions. For example, when the load increases, the target value may be appropriately increased to ensure system stability and efficiency.

[0055] In S120, when the DC output voltage is greater than the target output voltage value, the phase delay between the control signals of the first half-bridge and the second half-bridge is dynamically adjusted to adjust the DC output voltage to be less than or equal to the target output voltage value.

[0056] In this embodiment, when the DC output voltage exceeds the target value, the control unit dynamically adjusts the internal phase-shift delay between the control signals of the first and second half-bridges. The internal phase-shift delay refers to the phase difference between the control signals of the two half-bridges. By adjusting this phase difference, the output characteristics of the inverter circuit can be changed, thereby adjusting the DC output voltage.

[0057] When the system detects that the converter is under light load or no-load conditions, the control unit adjusts the phase relationship between the control signals of the first and second half-bridges, introducing an internal phase-shift delay. The introduction of the internal phase-shift delay causes the switching actions of the two half-bridges to no longer be completely synchronized, but rather to have a certain phase difference.

[0058] This internal phase-shift delay ensures that the AC output voltage of the inverter full-bridge circuit on the primary side of the isolation transformer reaches a zero-level interval at the end of each switching half-cycle. The timing of this zero-level interval is precisely controlled to ensure that the AC output voltage has dropped to zero before parasitic capacitance resonance causes reverse power transfer, thus effectively preventing reverse power transfer.

[0059] Because the zero-level interval is precisely controlled just before the parasitic capacitance resonance causes reverse power transfer, the power transfer path that would lead to output overvoltage due to this parasitic resonance is actively cut off, thereby reducing or even avoiding output overvoltage problems caused by parasitic resonance. This reduces the cost of light-load overvoltage suppression, optimizes the suppression effect, and improves the reliability of the DC transformer.

[0060] In this way, by introducing an internal phase-shift delay, the resonant DC transformer can effectively solve the output overvoltage problem under light load or no-load conditions without increasing additional hardware costs. This control strategy mainly relies on software adjustment and control algorithms, without requiring additional hardware devices. It can suppress light load overvoltage with low control complexity without adding components, thus reducing the cost of suppressing light load overvoltage in resonant DC transformers.

[0061] Furthermore, the introduction of internal phase-shift delay not only reduces costs but also optimizes the suppression of light-load overvoltage. By precisely controlling the creation of the zero-level interval, reverse power transfer caused by parasitic resonance can be effectively avoided, thereby ensuring the stability and accuracy of the output voltage. This effectively prevents output overvoltage problems caused by parasitic resonance and improves the reliability of the resonant DC transformer.

[0062] In combination with the above Figure 2 For example, to facilitate understanding of the overvoltage suppression method for the resonant DC transformer provided in this application, please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram illustrating the principle of a resonant DC transformer switching transistor control strategy according to an embodiment of this application. Figure 3 In the diagram, T1-T4 are the trigger signals for the fully controlled devices. V ab This is the AC output voltage of the inverter full-bridge circuit. V cd This is the AC input voltage of the rectifier bridge circuit. ir This is the resonant inductor current.

[0063] In this example, under the premise that T1 and T2 in the first half-bridge are not turned on at the same time, and T3 and T4 in the second half-bridge are not turned on at the same time, the control signals of the second half-bridge (T3 and T4) are delayed for a time equal to the aforementioned internal phase-shift delay D.

[0064] In this example, when the resonant DC transformer is detected to be under light load or no-load conditions, an internal phase-shift delay D is introduced between the control signals of the first half-bridge (e.g., T1, T2) and the second half-bridge (e.g., T3, T4) of the inverter full-bridge circuit driven by the isolation transformer. The function of this internal phase-shift delay D is to force the AC output voltage of the primary-side inverter circuit to... V ab The system enters a zero-level interval in advance; the timing of the zero-level interval is precisely controlled before the parasitic capacitance resonance is about to generate reverse power transmission, thereby actively cutting off the power transmission path caused by the parasitic resonance that would lead to output overvoltage, thus achieving reliable overvoltage suppression of the resonant DC transformer.

[0065] Optionally, according to some embodiments of this application, more specifically, the value of the inner phase delay is within a preset range; The upper limit of the preset range is calculated based on the physical parameters of the resonant DC transformer; The physical parameters include at least one of the following: the turns ratio of the isolation transformer, the number of diodes connected in series in a single half-bridge of the rectifier bridge circuit, the resonant inductance in the resonant circuit, the parasitic capacitance of the secondary diodes of the isolation transformer, and the dynamic voltage equalization capacitance of the secondary diodes of the isolation transformer.

[0066] The aforementioned preset range is determined based on the system design and operational requirements of the resonant DC transformer. The upper and lower limits of this preset range ensure stable system operation under various operating conditions.

[0067] In this embodiment, to ensure that the value of the internal phase-shift delay can effectively suppress the light-load overvoltage problem without negatively impacting the normal operation of the system, the upper limit of the preset range is calculated based on the physical parameters of the resonant DC transformer. These physical parameters directly affect the system's behavior under light-load or no-load conditions. Therefore, based on these physical parameters, it is possible to effectively ensure operational reliability while suppressing light-load overvoltage.

[0068] Optionally, according to some embodiments of this application, the value of the inner phase-shift delay is within a preset range, including: The values ​​of the inward phase delay satisfy the target relation, which includes: (1) In equation (1), D is the internal phase-shift delay, n is the turns ratio of the isolation transformer, and m is the number of diodes connected in series in a single half-bridge of the rectifier bridge circuit. This refers to the resonant inductance in a resonant circuit. For the parasitic capacitance of the secondary diode of the isolation transformer, Dynamic voltage equalization capacitor for the secondary diodes of the isolation transformer.

[0069] In this embodiment, the foregoing is continued. Figure 3 As shown, by adding an inner phase-shift delay, it is possible to achieve the following: The AC output voltage V of the inverter full-bridge circuit ab Reducing the value to 0 avoids power transfer caused by the current during the charging and discharging process of the voltage equalizing capacitor, thereby suppressing output overvoltage. When D reaches its maximum value, the no-load overvoltage phenomenon can be eliminated.

[0070] Therefore, by accurately calculating and dynamically adjusting the value of the internal phase shift delay, the light-load overvoltage problem of resonant DC transformers can be effectively suppressed, thereby improving the overall operational stability and reliability.

[0071] Optionally, according to some embodiments of this application, when the DC output voltage is greater than the target output voltage value, dynamically adjusting the inner phase-shift delay between the control signals of the first half-bridge and the second half-bridge includes: When the DC output voltage is greater than the target output voltage value, the internal phase shift delay is increased by using proportional-integral control through the output voltage closed-loop controller.

[0072] Optionally, according to some embodiments of this application, the overvoltage suppression method for a resonant DC transformer further includes: When the DC output voltage is less than the target value, the internal phase shift delay is reduced by proportional-integral control through the output voltage closed-loop controller, so that the resonant DC transformer is under normal load conditions and the internal phase shift delay is reduced to zero.

[0073] Please see details. Figure 4 , Figure 4 This is a control block diagram of an overvoltage suppression method for a resonant DC transformer provided in one embodiment of this application. To achieve the above control, this embodiment of the application uses an output voltage closed-loop controller for proportional-integral (PI) regulation.

[0074] like Figure 4 As shown, where, This is the rated output voltage of the DC transformer. The target output voltage value mentioned above represents the maximum acceptable output voltage. 1 / 2 f m This is the maximum value of the aforementioned internal phase-shift delay D. It is an acceptable overvoltage factor, which can be selected, for example, 1.04.

[0075] The embodiments of this application automatically adjust the output voltage using a closed-loop controller (such as a PI controller). The current actual output voltage, when Exceeding the above acceptable target output voltage value At that time, PI control is used to dynamically increase the internal phase shift delay D. As the power increases, Descending to Subsequently, the internal phase-shift delay D gradually decreases to zero. Under no-load conditions, using this control, the system's output overvoltage can be stably limited to within 4%.

[0076] When the converter is under normal load conditions, the aforementioned internal phase-shift delay D automatically decreases to zero, allowing the inverter full-bridge circuit to return to the conventional phase-shift control or duty cycle control mode, without affecting normal operation, thereby significantly improving the overall reliability of operation.

[0077] Optionally, according to some embodiments of this application, when the resonant DC transformer is a three-phase resonant DC transformer, the inverter full-bridge circuit further includes a third half-bridge, and the overvoltage suppression method for the resonant DC transformer further includes: When the three-phase resonant DC transformer is detected to be under light load or no load conditions, the third half-bridge in the inverter full-bridge circuit is controlled to be turned off.

[0078] In this embodiment, when applied to a three-phase resonant DC transformer, if the three-phase resonant DC transformer is detected to be under light load or no-load conditions, the third half-bridge in the inverter full-bridge circuit is controlled to shut down any one of the three phases, temporarily switching the inverter full-bridge circuit in the three-phase resonant DC transformer to a two-phase operation mode. This way, the circuit switching to the two-phase operation mode... Figure 2 Similarly, the above methods can be flexibly used to suppress overvoltage, thereby utilizing the characteristics of two-phase operation to suppress output overvoltage.

[0079] It should be noted that a three-phase resonant DC transformer typically includes three "phases" or three "arms" (A, B, and C), with each arm being a half-bridge. In this embodiment, among the three corresponding half-bridges (A, B, and C), any one corresponding half-bridge can be flexibly selected according to actual needs and turned off as the aforementioned "third half-bridge." The remaining two corresponding half-bridges are respectively designated as the "first half-bridge" and "second half-bridge" in the aforementioned embodiment.

[0080] For example, the half-bridge corresponding to A can be designated as the "third half-bridge," and the other two corresponding half-bridges can be designated as the "first half-bridge" and "second half-bridge" in the aforementioned embodiments. As another example, the half-bridge corresponding to B can be designated as the "third half-bridge," and the other two corresponding half-bridges can be designated as the "first half-bridge" and "second half-bridge" in the aforementioned embodiments. As yet another example, the half-bridge corresponding to C can be designated as the "third half-bridge," and the other two corresponding half-bridges can be designated as the "first half-bridge" and "second half-bridge" in the aforementioned embodiments.

[0081] Overall, the core idea of ​​the above embodiments of this application is that, instead of passively changing the system resonance parameters, it actively introduces a precisely calculated internal phase-shift delay in each half-cycle after identifying a light-load condition. This forces the AC output voltage of the inverter full-bridge circuit to be clamped to zero within the critical time window when the parasitic capacitance is about to transfer excess power to the load through resonance. Thus, it eliminates the light-load overvoltage phenomenon at its source without affecting normal operation or adding hardware. Therefore, the overvoltage suppression method for resonant DC transformers provided by the embodiments of this application, compared with existing technologies, reduces the cost of light-load overvoltage suppression, optimizes the suppression effect, and improves the reliability of the DC transformer.

[0082] Based on the overvoltage suppression method for resonant DC transformers provided in the above embodiments, and with the same inventive concept, this application also provides an overvoltage suppression device for a resonant DC transformer corresponding to the above-described overvoltage suppression method. The following describes...Figure 3 The overvoltage suppression device for resonant DC transformers is described in detail.

[0083] Based on the same inventive concept, in a second aspect, embodiments of this application provide a resonant DC transformer, which includes an inverter full-bridge circuit, a resonant circuit, an isolation transformer, and a rectifier bridge circuit. The input terminal of the inverter full-bridge circuit is connected to the DC input port, the output terminal of the inverter full-bridge circuit is electrically connected to the input terminal of the resonant circuit, the output terminal of the resonant circuit is electrically connected to the primary winding of the isolation transformer, the secondary winding of the isolation transformer is electrically connected to the input terminal of the rectifier bridge circuit, and the output terminal of the rectifier bridge circuit is electrically connected to the DC output port. The inverter full-bridge circuit includes a first half-bridge and a second half-bridge disposed between the DC input ports; The resonant DC transformer employs the overvoltage suppression method of the resonant DC transformer as described in any embodiment of the first aspect of this application.

[0084] Based on the overvoltage suppression method for resonant DC transformers provided in the above embodiments, and with the same inventive concept, this application also provides an overvoltage suppression device for a resonant DC transformer corresponding to the above-described overvoltage suppression method. The following describes... Figure 5 The overvoltage suppression device for resonant DC transformers is described in detail.

[0085] Figure 5 A schematic diagram of an overvoltage suppression device for a resonant DC transformer according to an embodiment of this application is shown. The resonant DC transformer includes: an inverter full-bridge circuit, a resonant circuit, an isolation transformer, and a rectifier bridge circuit; The input terminal of the inverter full-bridge circuit is connected to the DC input port, the output terminal of the inverter full-bridge circuit is electrically connected to the input terminal of the resonant circuit, the output terminal of the resonant circuit is electrically connected to the primary winding of the isolation transformer, the secondary winding of the isolation transformer is electrically connected to the input terminal of the rectifier bridge circuit, and the output terminal of the rectifier bridge circuit is electrically connected to the DC output port. The inverter full-bridge circuit includes a first half-bridge and a second half-bridge positioned between the DC input ports. Figure 5 The overvoltage suppression device 500 of the resonant DC transformer shown includes: The first detection module 510 is used to detect the DC output voltage provided by the DC output port and compare the DC output voltage with the target value of the output voltage of the resonant DC transformer. The first adjustment module 520 is used to dynamically adjust the inner phase-shift delay between the control signals of the first half-bridge and the second half-bridge when the DC output voltage is greater than the target output voltage value, so as to adjust the actual output voltage to be less than or equal to the target output voltage value.

[0086] This application provides an overvoltage suppression device for a resonant DC transformer. By setting corresponding functional modules, it detects the DC output voltage provided at the DC output port and compares it with the target output voltage value of the resonant DC transformer. When the DC output voltage exceeds the target value, the internal phase-shift delay between the control signals of the first and second half-bridges is dynamically adjusted to bring the DC output voltage down to or below the target value. Thus, this overvoltage suppression device for a resonant DC transformer, addressing the situation where the output voltage of the resonant DC transformer exceeds its rated value under light load or no-load conditions, can suppress light-load overvoltage with low control complexity without adding components. This reduces the cost of suppressing light-load overvoltage in resonant DC transformers and improves their reliability.

[0087] Optionally, according to some embodiments of this application, the value of the inner phase-shift delay is within a preset range; The upper limit of the preset range is calculated based on the physical parameters of the resonant DC transformer; The physical parameters include at least one of the following: the turns ratio of the isolation transformer, the number of diodes connected in series in a single half-bridge of the rectifier bridge circuit, the resonant inductance in the resonant circuit, the parasitic capacitance of the secondary diodes of the isolation transformer, and the dynamic voltage equalization capacitance of the secondary diodes of the isolation transformer.

[0088] Optionally, according to some embodiments of this application, the value of the inner phase-shift delay is within a preset range, including: The values ​​of the inward phase delay satisfy the target relation, which includes:

[0089] Where D is the internal phase-shift delay, n is the turns ratio of the isolation transformer, and m is the number of diodes connected in series in a single half-bridge of the rectifier bridge circuit. This refers to the resonant inductance in a resonant circuit. For the parasitic capacitance of the secondary diode of the isolation transformer, Dynamic voltage equalization capacitor for the secondary diodes of the isolation transformer.

[0090] Optionally, according to some embodiments of this application, when the DC output voltage is greater than the target output voltage value, dynamically adjusting the inner phase-shift delay between the control signals of the first half-bridge and the second half-bridge includes: When the DC output voltage is greater than the target output voltage value, the internal phase shift delay is increased by using proportional-integral control through the output voltage closed-loop controller.

[0091] Optionally, according to some embodiments of this application, the overvoltage suppression device for the resonant DC transformer further includes: The second adjustment module is used to reduce the internal phase shift delay by using proportional-integral control through the output voltage closed-loop controller when the DC output voltage is less than the target value, so that the resonant DC transformer is under normal load conditions and the internal phase shift delay is reduced to zero.

[0092] Optionally, according to some embodiments of this application, when the resonant DC transformer is a three-phase resonant DC transformer, the inverter full-bridge circuit further includes a third half-bridge, and the overvoltage suppression device of the resonant DC transformer further includes: The first control module is used to control the shutdown of the third half-bridge in the inverter full-bridge circuit when the three-phase resonant DC transformer is detected to be under light load or no load conditions.

[0093] Optionally, according to some embodiments of this application, the resonant circuit includes a resonant capacitor and a resonant inductor; The first terminal of the resonant capacitor is electrically connected to the first terminal of the output of the inverter full-bridge circuit, the second terminal of the resonant capacitor is electrically connected to the first terminal of the resonant inductor, and the second terminal of the resonant inductor is electrically connected to the first terminal of the primary winding of the isolation transformer. The second terminal of the output of the inverter full-bridge circuit is electrically connected to the second terminal of the primary winding of the isolation transformer.

[0094] Optionally, according to some embodiments of this application, the first half-bridge includes a first switch module and a second switch module, and the second half-bridge includes a third switch module and a fourth switch module; The first terminal of the first switch module and the first terminal of the third switch module are electrically connected to the positive terminal of the DC input port. The second end of the first switch module and the first end of the second switch module are electrically connected to the first node, and the second end of the third switch module and the first end of the fourth switch module are electrically connected to the second node. The second terminal of the second switch module and the second terminal of the fourth switch module are electrically connected to the negative terminal of the DC input port, respectively. The first node is electrically connected to the first terminal of the output of the inverter full-bridge circuit, and the second node is electrically connected to the negative terminal of the output of the inverter full-bridge circuit.

[0095] Optionally, according to some embodiments of this application, the rectifier bridge circuit includes a fourth half-bridge and a fifth half-bridge, the fourth half-bridge including a fifth switching module and a sixth switching module, and the fifth half-bridge including a seventh switching module and an eighth switching module; The first terminal of the fifth switch module and the first terminal of the seventh switch module are electrically connected to the first terminal of the DC output port; The second end of the fifth switch module and the first end of the sixth switch module are electrically connected to the first end of the secondary winding of the isolation transformer, respectively; the second end of the seventh switch module and the first end of the eighth switch module are electrically connected to the second end of the secondary winding of the isolation transformer, respectively. The second terminal of the sixth switch module and the second terminal of the eighth switch module are electrically connected to the second terminal of the DC output port; wherein, the fifth switch module, the sixth switch module, the seventh switch module and the eighth switch module include at least one diode.

[0096] Based on the overvoltage suppression method for resonant DC transformers provided in the above embodiments, and with the same inventive concept, this application also provides an overvoltage suppression device for a resonant DC transformer corresponding to the above-described overvoltage suppression method. The following describes... Figure 6 This paper provides a detailed introduction to overvoltage suppression equipment for resonant DC transformers.

[0097] Please see below. Figure 6 , Figure 6 This is a schematic diagram of the overvoltage suppression device for a resonant DC transformer provided in one embodiment of this application.

[0098] The overvoltage suppression device for a resonant DC transformer may include a processor 601 and a memory 602 storing computer program instructions.

[0099] Specifically, the processor 601 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0100] Memory 602 may include mass storage for data or instructions. For example, and not limitingly, memory 602 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 602 may include removable or non-removable (or fixed) media. Where appropriate, memory 602 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 602 is non-volatile solid-state memory.

[0101] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the methods according to one aspect of this disclosure.

[0102] The processor 601 reads and executes computer program instructions stored in the memory 602 to implement any of the overvoltage suppression methods for resonant DC transformers in the above embodiments.

[0103] In one example, the overvoltage suppression device for the data resonant DC transformer may further include a communication interface 603 and a bus 610. Wherein, as Figure 6 As shown, the processor 601, memory 602, and communication interface 603 are connected through bus 610 and complete communication with each other.

[0104] The communication interface 603 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0105] Bus 610 includes hardware, software, or both, that couples components of the overvoltage suppression device for the resonant DC transformer together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 610 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnect is contemplated herein.

[0106] The overvoltage suppression device of the resonant DC transformer performs the overvoltage suppression method of the resonant DC transformer in the embodiments of this application, thereby realizing the overvoltage suppression method of the resonant DC transformer described in the embodiments of this application.

[0107] Furthermore, in conjunction with the overvoltage suppression method for the resonant DC transformer in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the overvoltage suppression methods for the resonant DC transformer in the above embodiments.

[0108] Based on the overvoltage suppression method for resonant DC transformers in the above embodiments, this application provides a computer program product. When the instructions in the computer program product are executed by the processor of an electronic device, the electronic device performs the overvoltage suppression method for resonant DC transformers as provided in any of the above embodiments of this application.

[0109] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0110] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0111] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0112] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0113] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method of suppressing overvoltage of a resonant DC transformer, characterized by, The resonant DC transformer comprises an inverter full-bridge circuit, a resonant circuit, an isolation transformer and a rectifier bridge circuit; An input end of the inverter full-bridge circuit is connected with a DC input port, an output end of the inverter full-bridge circuit is electrically connected with an input end of the resonant circuit, an output end of the resonant circuit is electrically connected with a primary winding of the isolation transformer, a secondary winding of the isolation transformer is electrically connected with an input end of the rectifier bridge circuit, and an output end of the rectifier bridge circuit is electrically connected with a DC output port; The inverter full-bridge circuit comprises a first half-bridge and a second half-bridge arranged between the DC input port, and the overvoltage suppression method of the resonant DC transformer comprises: detecting a DC output voltage provided by the DC output port, and comparing the DC output voltage with an output voltage target value of the resonant DC transformer; in a case where the DC output voltage is greater than the output voltage target value, dynamically adjusting an internal phase shift delay between control signals of the first half-bridge and the second half-bridge to adjust the DC output voltage to be less than or equal to the output voltage target value.

2. The method of claim 1, wherein, The value of the internal phase shift delay is in a preset range; An upper limit value of the preset range is calculated based on physical parameters of the resonant DC transformer; The physical parameters comprise at least one of a transformation ratio of the isolation transformer, a series number of diodes in a single half-bridge in the rectifier bridge circuit, a resonant inductance in the resonant circuit, a parasitic capacitance of a secondary diode of the isolation transformer, and a dynamic voltage-sharing capacitance of the secondary diode of the isolation transformer.

3. The method of claim 2, wherein, The value of the internal phase shift delay is in a preset range, comprising: The value of the internal phase shift delay satisfies a target relationship, and the target relationship comprises: Wherein, D is the inner phase shift delay, n is the transformation ratio of the isolation transformer, m is the series number of diodes in a single half-bridge in the rectifier bridge circuit, is the resonant inductance in the resonant circuit, is the parasitic capacitance of the secondary side diode of the isolation transformer, is the dynamic voltage sharing capacitance of the secondary side diode of the isolation transformer.

4. The method of claim 1, wherein, The dynamically adjusting the internal phase shift delay between the control signals of the first half-bridge and the second half-bridge in the case where the DC output voltage is greater than the output voltage target value comprises: In the case where the DC output voltage is greater than the output voltage target value, the output voltage closed-loop controller increases the internal phase shift delay by proportional-integral control.

5. The method of claim 4, wherein, The method further comprises: In the case where the DC output voltage is less than the output voltage target value, the output voltage closed-loop controller decreases the internal phase shift delay by proportional-integral control, so that the resonant DC transformer is in a normal load working condition, and the internal phase shift delay is decreased to zero.

6. The method of claim 1, wherein, In the case where the resonant DC transformer is a three-phase resonant DC transformer, the inverter full-bridge circuit further comprises a third half-bridge, and the method further comprises: In the case where it is detected that the three-phase resonant DC transformer is in a light load or no-load working condition, the third half-bridge in the inverter full-bridge circuit is controlled to be turned off.

7. The method according to any one of claims 1 to 6, characterized in that, The resonant circuit comprises a resonant capacitance and a resonant inductance; A first pole of the resonant capacitance is electrically connected with a first end of the output end of the inverter full-bridge circuit, a second pole of the resonant capacitance is electrically connected with a first end of the resonant inductance, and a second end of the resonant inductance is electrically connected with a first end of the primary winding of the isolation transformer; The second end of the output end of the inverter full-bridge circuit is electrically connected to the second end of the primary winding of the isolation transformer.

8. The method according to any one of claims 1 to 6, characterized in that, The first half-bridge includes a first switch module and a second switch module, and the second half-bridge includes a third switch module and a fourth switch module; The first end of the first switch module and the first end of the third switch module are electrically connected to the positive electrode connection of the DC input port; The second end of the first switch module and the first end of the second switch module are electrically connected to a first node, and the second end of the third switch module and the first end of the fourth switch module are electrically connected to a second node; The second end of the second switch module and the second end of the fourth switch module are respectively electrically connected to the negative electrode connection of the DC input port; The first node is electrically connected to the first end of the output end of the inverter full-bridge circuit, and the second node is electrically connected to the negative electrode connection of the output end of the inverter full-bridge circuit.

9. The method according to any one of claims 1 to 6, characterized in that, The rectifier bridge circuit includes a fourth half-bridge and a fifth half-bridge, the fourth half-bridge includes a fifth switch module and a sixth switch module, and the fifth half-bridge includes a seventh switch module and an eighth switch module; The first end of the fifth switch module and the first end of the seventh switch module are electrically connected to the first end of the DC output port; The second end of the fifth switch module and the first end of the sixth switch module are respectively electrically connected to the first end of the secondary winding of the isolation transformer, and the second end of the seventh switch module and the first end of the eighth switch module are respectively electrically connected to the second end of the secondary winding of the isolation transformer; The second end of the sixth switch module and the second end of the eighth switch module are electrically connected to the second end of the DC output port; wherein at least one diode is included in the fifth switch module, the sixth switch module, the seventh switch module, and the eighth switch module.

10. A resonant DC transformer, characterized by The resonant DC transformer includes an inverter full-bridge circuit, a resonant circuit, an isolation transformer, and a rectifier bridge circuit; The input end of the inverter full-bridge circuit is connected to a DC input port, the output end of the inverter full-bridge circuit is electrically connected to the input end of the resonant circuit, the output end of the resonant circuit is electrically connected to the primary winding of the isolation transformer, the secondary winding of the isolation transformer is electrically connected to the input end of the rectifier bridge circuit, and the output end of the rectifier bridge circuit is electrically connected to a DC output port; The inverter full-bridge circuit includes a first half-bridge and a second half-bridge arranged between the DC input port; The resonant DC transformer adopts the overvoltage suppression method of the resonant DC transformer according to any one of claims 1-9.

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